Flow control valves for the water flush tank for toilets have heretofore comprised float actuated valves which have a valve element held in a closed position by the float when the tank is full. Prior art valves of this type have a float which is mechanically coupled to the valve element. Valves of this type have not been found completely satisfactory as the float must function to hold the valve closed against the inlet water pressure and the linkage necessary to effect direct mechanical coupling of the float is relatively complex and frequently becomes incorrectly adjusted after a prolonged period of use.
Float actuated valves of a type which have a valve element held in a closed position by the inlet water pressure and adapted to the vertically oriented mounting required for flush tanks are known in the prior art but these valves have not proven to be completely satisfactory. Valves illustrative of the known prior art are disclosed in U.S. Pat. Nos. 2,559,046 and 1,943,769. The valve element in patent No. 1,943,769 is of a construction and mounting which is actuated in a longitudinally axial direction only by a lever arm provided with a float. An inherent disadvantage of this type of valve construction and operation is that a relatively large force is required to axially displace the valve element on initial opening movement. Consequently, a valve of this type is generally restricted to relatively low pressure fluid systems.
A valve of the type illustrated in patent No. 2,559,046 discloses a valve element and lever arm combination of the preferred angular valve displacement type which requires a substantially lesser force to initiate opening of the valve. However, the valve disclosed in this patent is not adaptable for use in a flush tank as it is incapable of providing the necessary divided flow to the tank and to the overflow pipe.